The present embodiments relate to setup and configuration of positron emission tomography (PET) detectors. Using a ring of detectors, pairs of gamma rays generated by positrons may be detected. Any given pair of gamma rays travel about 180 degrees apart. To distinguish specific pairs, a coincidence of detected gamma rays is determined. The timing of receipt is used to pair the detected gamma rays. The position of the gamma rays detected by a ring of detectors is used to define a line of response for reconstruction of the imaged object from the gamma rays. In order to accurately identify the position and timing of the gamma rays, detectors may be setup before the first actual scan. Furthermore, the setup may be repeated on a regular basis to account for long-term drift of material and device properties. The setup may require calibration processes with multiple radiation sources to correct for non-linearity and timing performance.